Leptin is related to epinephrine levels but not reproductive hormone levels in cycling African-American and Caucasian women.

This study examined the effects of the menstrual cycle and race on plasma leptin levels. Sixty-one healthy African-American and Caucasian women and men (mean age 32 years) were studied twice, approximately six weeks apart, women once during the follicular phase (days 7-10 following menses) and once during the luteal phase (days 7-10 following LH surge) of the menstrual cycle. Consistent with the literature, women showed approximately 4-fold higher leptin levels as compared to men (p<0.001). There were no effects of the menstrual cycle nor race on leptin levels. Leptin levels were correlated with BMI in both women and men respectively, r=0.602, p<0.001 and r=0.338, p<0.05. Leptin levels showed a high degree of test-retest reliability across the 6-week testing interval (r=0.62, p<0.001 for women and r=0.91, p<0.001 for men). In addition, in women, and independent of BMI, leptin was negatively correlated with plasma epinephrine levels (r=-0.38, p=0.01). No such relationship was observed in men. The findings indicate that in women leptin levels are not associated with cyclic changes in estrogen or progesterone but may be associated with catecholamine levels.